With the advent of optical communications systems, considerable development work has been done on methods for assembling components of such systems. One of the problems associated with assembling such components is a need for precise alignment of optical elements such as lenses, optical fibers, lasers, mirrors and photodetectors. It is important that factory methods be developed for assembling optical devices and packages in an efficient manner, with a minimum requirement of operator skill, but with an exceedingly high degree of precision.
In making laser modules, for example, it is necessary to bond an optical fiber in precise alignment to a semiconductor laser to maximize the portion of the laser output that is directed into the end of the optical fiber. For obtaining maximum optical coupling, it is typically desired that the center of the optical fiber be aligned with the center of the laser to within tolerances of less than one micron. The most common way of making this alignment is a process known as "active alignment," in which light is emitted from the laser, with the position of the end of the optical fiber near the laser being adjusted until the light transmitted through the fiber reaches a maximum.
For automatic assembly of laser modules using active alignment, it is usually required that some apparatus be devised for causing one end of the optical fiber to scan a small area intercepting the laser output beam, while a photodetector at the output end of the fiber detects the location at which maximum light transmission occurs. When that position has been determined, the optical fiber is permanently bonded to the laser and enclosed within a package.
It can be appreciated that mechanical scanning of an optical device such as an optical fiber is inherently time consuming, and, as the need for greater volumes of mass-produced components increases, such time consumption becomes increasingly detrimental. Of course, the alternative of manually adjusting the fiber orientation to achieve active alignment is even less practical because of the operator skill required, as well as the time consumed. Accordingly, there is a continued, long-felt need for better and more efficient methods for aligning, assembling and mass-producing optical and/or photonics components.